Democrats are preparing to grill Mike Waltz about the Signal chat scandal when he appears at a confirmation hearing to be the next U.S. Ambassador to the United Nations. NBC News’ Gabe Gutierrez reports more.

Waltz was at the center of the Signal chat controversy, in which a journalist was accidentally included in a discussion of sensitive military information.

President Donald Trump is replacing his National Security Adviser, Mike Waltz, and nominating him to be Ambassador to the United Nations, he announced Thursday, marking the first major personnel shake-up of Trump’s second term.